The present invention is related to an inductor, and especially to an inductor without a gap spacer.
As shown in FIGS. 1a and 1b, a conventional inductor 10 includes a bobbin 20, a U-shaped magnetic core member 30, an I-shaped magnetic core member 50, and a spacer 60. Several rounds of wires are wound on the bobbin 20 to be employed as a coil of the inductor 10. Because the magnetic core of the inductor 10 is constituted by the U-shaped magnetic core member 30 and the I-shaped magnetic core member 50, this inductor 10 is commonly called a xe2x80x9cUI inductorxe2x80x9d. The U-shaped magnetic core member 30 has a concavity 35 on a side wall thereof. The U-shaped magnetic core member 30 is engaged with the bobbin 20 but the opening of the central hole of the bobbin 20 is exposed out of the concavity 35 of the U-shaped magnetic core member 30. The spacer 60 is disposed between the adjacent magnetic core members 30, 50 to space the core members out of contact with each other, thereby reducing magnetic interference therebetween. The spacer 60 may be made of a non-magnetic material, such as plastic, aluminum or paint, which does not cause any magnetic interference between the two magnetic core members 30, 50 and the two magnetic core members 30, 50 may be fixed and held through the spacer 60 with a certain space therebetween. Typically, this spacer 60 is made of an insulating material and adhered to one end of the I-shaped magnetic core member 50. The end of the I-shaped magnetic core member 50 with the spacer 60 is inserted into the central hole of the bobbin 20 through the concavity 35 for allowing the spacer 60 to be attached to the U-shaped magnetic core member 30 so as to assemble the inductor 10 as shown in FIG. 1a. Briefly, the function of the spacer 60 is to form a gap between the I-shaped magnetic core member 50 and the U-shaped magnetic core member 30 so that the inductance of the inductor 10 can be changed by adjusting the spacer size.
However, when manufacturing such an inductor, there exists some problems as follows.
(1) When the I-shaped magnetic core member 50 is inserted into the hole of the bobbin 20, the spacer 60 may be adhered to the inner wall of the central hole of the bobbin 20 due to its adhesive property. If the I-shaped magnetic core member 50 is forcedly inserted into the bobbin 20, the spacer 60 may be deformed, thereby influencing the thickness of the spacer 60 and generating an error of the gap, so that the predetermined inductance can not be obtained.
(2) It is uneasy to precisely control the length of the I-shaped magnetic core member 50 inserted into the bobbin 20.
(3) One end of the I-shaped magnetic core member 50 is attached to the U-shaped magnetic core member 30 only through the spacer 60. When manufacturing the inductor, the gap may become larger because of the thermal expansion of the spacer so that the inductance of the inductor may be changed.
(4) If the gap is too large or the spacer 60 is too thick, the other end of the I-shaped magnetic core member 50 will be protruded over the edge of the bobbin 20, or even over the pin 70 of the bobbin 20, after inserting the I-shaped magnetic core member 50 into the central hole of the bobbin 20.
(5) The size of the spacer 60 must be matched with that of the central hole of the bobbin 20. If the size of the spacer 60 is too big, the I-shaped magnetic core member 50 can not be smoothly inserted into the central hole of the bobbin 20. If the size of the spacer 60 is too small, the spaced area between the I-shaped magnetic core member 50 and the U-shaped magnetic core member 30 may be insufficient.
Therefore, it is desirable to develop an inductor without any above-described drawbacks and without needing a spacer to form a gap.
An object of the present invention is to provide an inductor without a gap spacer. According to the present invention, the inductor includes a bobbin having at least one round of wire wound thereon to serve as a coil of the inductor, a first magnetic member coupled with the bobbin, and a second magnetic member having a first end and a second end, wherein the second magnetic member is inserted into the bobbin from its second end and the first end of the second magnetic member has a protrusion for allowing the second magnetic member to be partially inserted into the bobbin.
Preferably, the first magnetic member is a U-shaped type magnetic core member and the second magnetic member is an I-shaped type magnetic core member. The first and second magnetic members are made of one selected from a relatively soft magnetic material, Mnxe2x80x94Zn ferrite, Nixe2x80x94Zn ferrite and a silicon steel plate, respectively, and employed as a magnetic core of the inductor.
Preferably, the protrusion of the second magnetic member has a recess formed on an upper surface thereof for allowing a tool to be inserted therein so as to grab the second magnetic member. The recess can be a hole.
Preferably, the second magnetic member is shortened in accordance with a thickness of a reference piece so as to form a gap between the second end of the second magnetic member and the first magnetic member. The height of the reference piece is greater than that of the side wall of the first magnetic member with the concavity. Certainly, the reference piece is removed before the inductor is assembled.